Dicyclohexylcarbodiimide → N,N'-Dicyclohexylurea

HRID 2394218Notes

Reaction equation

HRID 2394218 reaction equation
[OH:1]C(COC1C=CC(C(O)=O)=CC=1)CN1CCN(CC(O)=O)CCN(CC(O)=O)CCN(CC(O)=O)CC1.[CH:39]1([N:45]=[C:46]=[N:47][CH:48]2[CH2:53][CH2:52][CH2:51][CH2:50][CH2:49]2)[CH2:44][CH2:43][CH2:42][CH2:41][CH2:40]1>N1C=CC=CC=1.C(N)=O>[C:46]([NH:45][CH:39]1[CH2:40][CH2:41][CH2:42][CH2:43][CH2:44]1)([NH:47][CH:48]1[CH2:53][CH2:52][CH2:51][CH2:50][CH2:49]1)=[O:1]

Participants

4

Reactant 2

HCID 10868DicyclohexylcarbodiimideHCID 15017889HCID 15017889, compound

Product 1

HCID 4277N,N'-Dicyclohexylurea

Reagents, catalysts & solvents 1

HCID 68494755HCID 68494755, compoundSolvent2×

Procedure

A solution of the gadolinium complex of 10-(2-hydroxy-3-(4-carboxyphenoxy)-propyl)-1,4,7-tris(carboxymethyl)-1,4,7,10-tetraazacyclododecane (500 mg, 0.72 mmol) in pyridine/formamide (1:1, 10 mL) was cooled to 0° C. with stirring. Dicyclohexylcarbodiimide (DCC, 149 mg, 0.72 mmol) and N,N-dimethylaminopyridine (DMAP, 20 mg, 0.16 mmol) were added. The resulting solution was stirred for 30 min at 0° C. A solution of dextran (MW 40,000; 1.0 g, 0.025 mmol) in formamide/pyridine (1:1, 30 mL) was prepared by gently warming a suspension of the polysaccharide. The dextran solution was added to the activated chelate and the mixture was stirred at 25° C. for 4 days. During this time a precipitate of dicyclohexylurea formed. The suspension was filtered and the polysaccharide was precipitated by dropwise addition of the filtrate into ethanol/ether (1:2, 300 mL). The suspension was stirred for 30 min then allowed to settle. The solvent was decanted off and the solid was isolated by filtration. The product was purified by GPC on a column of Sephadex G-25 eluted with distilled H2O. Fractions corresponding to the macromolecular component were collected, pooled and lyophilized. To ensure there were no small molecular components unremoved by GPC an analytical sample was prepared by ultrafiltration (Centrex MWCO 10,000) of an aqueous solution (500 μL) containing the product (300 mg). The retentate was collected and lyophilized giving a white pad (296 mg). The UV spectrum of an aqueous solution of this product (0.175 mg/mL) had an absorbance at 258 nm which confirmed the presence of the benzoic acid ester. The analytical sample contained 0.92% gadolinium, corresponding to approximately 3 mol Gd/mol dextran.

Workup

  1. stirringThe resulting solution was stirred for 30 min at 0° C
  2. temperatureby gently warming
  3. stirringthe mixture was stirred at 25° C. for 4 days

Sources & evidence

ORD record
ord-2798021e18f244e5bd9ecd528e7d0a3e
Source dataset
uspto-grants-1998_09
Patent number
US05811076

Reaction notes

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